Microstructures and mechanical properties of equal channel angular pressed 5083 Al alloy

An ultra-fine grained (UFG) structure was introduced in a commercial 5083 Al alloy with an initial grain size of similar to 200 mum using the equal channel angular pressing (ECAP) technique. ECAP was successfully conducted at 473 K on the same sample up to a total of 8 pressings through the die such that the sample was rotated 180 degrees around its longitudinal axis between pressings. The microstructure was reasonably homogeneous after a single pressing and consisted of parallel bands of elongated substructure having an average width of 0.2 mum and an average length of 0.8 mum. An equiaxed ultra-fine grained structure of similar to 0.3 mum was obtained in the present alloy after 4 pressings. The ultra-fine grains were thermally stable at 523 K. The yield stress of as-received 5083 Al alloy was 129 MPa, whereas it increased to 249 MPa after a single pressing and finally became 290 MPa after 8 pressings, which was superior to that of a conventional 5083-H321 Al alloy. In addition, in this study, the feasibility of low temperature superplasticity of a UFG 5083 Al alloy was examined. It was found that the 5083 Al alloy with a grain size of similar to 0.3 mum exhibited a superplastic-like behavior with elongation to failure in excess of 200% below 523 It.